Automatic safety switch eob badio appabatus



July 26, 1932. M. T. M CONN ELL AUTOMATIC SAFETY SWI TCH FOR RADIO APPARATUS Filed July 22, 1930 Patented July 26, 1932 PTENT FFECE MAX '1. MCCONNELL, OF wEsTFIELDpPENNSYLvANIA, ASSIGNOR OF ONE-HALF T ARTHUR R. EUGABER, OF WESTFIELID, PENNSYLVANIA AUTOMATIC SAFETY SVTITCI-I FOR RADIO APPARATUS Application filed July 22,

This invention relates to radioreceiving apparatus, and has for one of its objects to provide novel means which shall be adapted to afiord apparatus of this character the greatest possible protection against injury by light- The invention has for a further object to provide means of the character stated which shall be adapted to function automatically and immediately on the stopping or turning off of the radio receivingapparatus to protect the apparatus against injury by lightning.

To attain the foregoing and other objects, the nature of which will appear as the description proceeds, the invention comprehends the provision of a power switch for a radio receiving apparatus which shall be adapted, when in off position to ground the antenna, the primary coil of the radio frequency transformer,

and the primary coil of the power transformer of the apparatus.

The invention further comprehends the provision of a-power switch of the character stated which shall be adapted, when in on position, to connect the primary coil of the radio frequency transformer to the antenna and connect the primary coil of the power transformer to the source of current, and which shall be adapted when in off position, to dis connect the primary coil of the radio frequency transformer from the antenna and ground the coil and antenna and to disconnect the primary coil of the power transformer from the source of current and ground both terminals of this coil.

The invention is hereinafter more fully described and claimed, and illustrated in the accompanying drawing, wherein Figure 1 is a diagrammatic view of a portion of a radio receiving apparatus embodying the automatic safety power switch, the switch being shown in on position;

Figure 2 is a similar view with the switch in on position, and

Figure 3 is a sectional view taken on a plane extending vertically and centrally through the switch and the panel of the apparatus on which the switch is mounted.

The power switch is adapted to be used in 1930. Serial No. 469,861.

apparatus. There are illustrated in the drawing only such parts of a radio receiving apparatus as are necessary to illustrate the application and operation of the switch, such parts comprising an antenna 1, an antenna coupling shown as consisting of a radio frequency transformer 2, a power transformer 3, a generator 4, and the antenna post 4a.

The switch comprises a fixed plate or stator 5, and a movable plate or rotor 6. The switch is adapted to be arranged within the radio receiving apparatus and secured to the panel 7 thereof. The stator 5 is secured to the panel 7 by a sleeve 8 and nut 9. The sleeve 8 is fixed at one end to the center of the stator 5 and passes through the panel 7, and the nut 9 is engaged with the outer end of the sleeve and contacts with the outer face of the panel. The sleeve 8 constitutes a bearing and journaled therein is a shaft 10. The rotor 6 is fixed to the inner end of the shaft 10 by nuts 11, and a knob 12 is fixed to the outer end of the shaft by a set screw 13.

The stator 5 and rotor 6 are made of bakelite or any other suitable insulating material and they are preferably of circular formation. The stator 5 is provided at its periphery with binding posts 14, 15, 16, 17, 18 and 19, and it is provided at its inner face with contacts 20, 21, 22, 23, 24 and 25 connected respectively to the binding posts 14-19. The binding posts 14, 16 and 18 are connected by a conductor 26 which is grounded, as illustrated at 27.

The rotor 6 is smaller diametrically than the stator 5 and is provided at its inner face with binding posts 28, 29, 30 and 31 and it is provided with contacts 32, 33, 34 and 35 connected respectively to the binding posts 28-31.

The antenna post 464 is connected by a lead 36 to the bindingpost 28 of the rotor 6 and the primary coil of the radio frequency transformer 2 has one end grounded, as shown at 37, and has its other end connected by a lead 38 to the binding post 19 of the stator 5. The generator 4 is connected by conductors 39 and 40 to the binding posts 15 and 17 of the stator 5. The primary coil of the power transformer 3 has its terminals connected by conductors 41 and 42 to the binding post 29 and 30 of the rotor 6. The binding post 31 of the rotor 6 is connected to the contact 24: of the stator 5 by a conductor or pigtail 43.

When the switch is in off position, the contacts 32, 33, 34 and 35 of the rotor 6 engage the contacts 20, 22, 24, and 25 of the stator 5, and in View thereof, the antenna post 4a, both terminals of the primary coil of the radio frequency transformer 2, and both terminals of the primary coil of the power transformer 3 are grounded, with the result that the apparatus is fully protected against injury by lightning.

Then the switch is in on position, the contacts 32, 33 and 3 1 of the rotor 6 engage the contacts 21, 22, 23 and 25, respectively, of the stator 5, with the result that the primary coil of the radio frequency transformer 2 is connected to the antenna post 4a and the primary coil of the power transformer 3 is connected to the generator 4.

' From the foregoing description, taken in connection with the accompanying drawing, it should be apparent that the switch functions automatically, on being turned into off position, to protect the radio apparatus against injury by lightning, that this protection is the greatest that can be provided due to the fact that the antenna and both terminals of the primary coils of the radio frequency and power transformers are grounded, and that the switch is simple and inexpensive and capable of being readily applied to a radio receiving set of any type.

While I have described the principle of the invention, together with the structure which I now consider the preferred embodiment thereof, it is to be understood that the structure shown is merely illustrative and that such changes may be made, when desired, as fall within the scope of the invention as claimed.

I claim 1. In a radio receiving apparatus, an antenna, a radio frequency transformer, a power transformer and source of current therefor, and a switch adapted when in on position to connect the antenna to one terminal of the primary coil of said first transformer and to connect the terminals of the primary coil of said second transformer to said source of current and adapted when in off position to disconnect the antenna and source of current from said terminals and connect the antenna and said terminals to the ground.

2. In a radio receiving apparatus, a series of fixed contacts, a radio frequency transformer having one terminal of its primary coil connected to one of the contacts, a source of current connected to the other contacts, a a second series of fixed contacts connected to the ground, a rotor having a series of contacts, an antenna connected to one of said third series of contacts, a power transformer having its terminals connected to two of said third series of contacts, the remaining contact of said third series being connected to one of said second series of contacts, and means for moving the rotor into on and 0E position, the contacts on the rotor engaging said first series of contacts when the rotor is in on position to connect the primary coil of the radio frequency transformer to the antenna and to connect the primary coil of the power transformer to the source of current, and said third series of contacts engaging said second series of contacts and one s of said first series of contacts when the rotor is in off position to ground the terminals of said coils.

3. In a radio receiving apparatus, an antenna post, an antenna coupling, a power transformer and source of current therefor, and a switch when in on position constituting the sole connection between said post and coupling and the sole connection between said source and transformer and when in off position disconnecting said post and coupling and said source and transformer and grounding said post, coupling and transformer.

In testimony whereof I hereunto affix my signature.

MAX T. MCCONNELL. 

